Power transmission device and communication method

Abstract

To appropriately transmit power from a power transmission device to a power reception device.SOLUTION: The power transmission apparatus 100, which wirelessly transmits power to one or more power reception apparatuses 200, derives data of power loss between the power transmission apparatus 100 and the power reception apparatuses 200 based on values of received power received from the power reception apparatuses, and performs foreign object detection based on the data of power loss. When a change in the power transmission / reception state in the power transmittable range of the power transmission device 100 is detected, the power transmission device 100 derives data of power loss again.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to wireless power transmission technology. [Background technology]

[0002] In recent years, technological development of wireless power transmission systems has been widespread. Patent Document 1 discloses a power transmitting device and a power receiving device that comply with the standard (WPC standard) established by the Wireless Power Consortium (WPC), a standardization organization for wireless charging standards. Patent Document 2 also discloses a foreign object detection method in the WPC standard. Here, a foreign object refers to a conductive object such as a metal piece. The WPC standard calculates in advance the power loss between the power transmitting device and the power receiving device when there is no foreign object based on the difference between the transmitted power at the power transmitting device and the received power at the power receiving device, and the calculated value is considered to be the power loss in the normal state (when there is no foreign object) during power transmission processing. Then, if the power loss calculated between the power transmitting device and the power receiving device during subsequent power transmission deviates by more than a threshold value from the reference power loss in the normal state, it is determined that a foreign object is present or that there is a possibility of a foreign object being present. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-56959 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-70074 Summary of the Invention [Problem to be solved by the invention]

[0004] In a power transmitting device capable of transmitting power to multiple power receiving devices simultaneously, when a first power receiving device and a second power receiving device are placed on the power transmitting device, the power loss between the power transmitting device and the first power receiving device may be affected by the second power receiving device. Similarly, the power loss between the power transmitting device and the second power receiving device may be affected by the first power receiving device. Therefore, if there is a change in the state (number, etc.) of the power receiving devices placed on the power transmitting device, the power loss between the power transmitting device and the power receiving device in the normal state that was calculated in advance also changes, resulting in a problem of reduced accuracy in foreign object detection.

[0005] The present invention has been made in view of the above-mentioned problems, and has an object to appropriately transmit power from a power transmitting device to a power receiving device. [Means for solving the problem]

[0006] As one means for solving the above problems, a power transmission device of the present invention has the following configuration: A power transmission device, a power transmitting means for wirelessly transmitting power to one or more power receiving devices; a communication means for communicating with the one or more power receiving devices; a derivation unit that derives data on power loss between the power transmitting unit and the power receiving unit based on a value of received power received from the power receiving unit via the communication unit; a foreign object detection means for detecting an object other than the power receiving device that performs the communication based on the data of the power loss; a detection means for detecting a change in a power transmission and reception state within a power transmission range of the power transmission device, When the detecting means detects a change in the power transmission / reception state while the power transmitting means is transmitting power to the power receiving device, the deriving means re-derives the power loss data. [Effects of the Invention]

[0007] This allows power to be transmitted appropriately from the power transmitting device to the power receiving device. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a block diagram illustrating a configuration example of a power transmission device. [Figure 2] FIG. 2 is a block diagram illustrating a configuration example of a power receiving device. [Figure 3] FIG. 2 is a block diagram illustrating an example of a functional configuration of a control unit of the power transmitting device. [Figure 4] 10 is a flowchart of a process executed by the power transmitting device. [Figure 5] 10 is an exemplary flowchart of a power transmission control process. [Figure 6] 10 is an exemplary flowchart of a calibration data re-derivation determination process. [Figure 7] 10 shows an operation sequence of a first processing example executed by the system. [Figure 8] 10 shows an operation sequence of a second processing example executed by the system. [Figure 9] 10 shows an operation sequence of a third processing example executed by the system. [Figure 10] 10 shows an example of power transmitting antenna (power transmitting coil) information held by a power transmitting device. [Figure 11] 10A and 10B are diagrams illustrating a foreign object detection method based on a power loss technique. [Figure 12] 1 shows an example of the configuration of a wireless power transmission system. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0010] [Foreign object detection method based on power loss technique] First, a foreign object detection method based on the power loss technique defined in the WPC (Wireless Power Consortium) standard will be described with reference to FIG. 11. FIG. 11 is a diagram illustrating the foreign object detection method based on the power loss technique. In FIG. 11, the horizontal axis represents the transmitted power of the power transmitting device, and the vertical axis represents the received power of the power receiving device. A foreign object is a conductive object such as a piece of metal, and is an object different from the power receiving device.

[0011] First, the power transmitting device transmits power to the power receiving device, and the power transmitting device receives from the power receiving device a received power value Pr1 (called Light Load) received by the power receiving device. The power transmitting device then stores the transmitted power value Pt1 at that time (point 1100). Here, the transmitted power value Pt1 or the received power value Pr1 is a predetermined minimum transmitted power or received power. At this time, the power receiving device controls the load so that the received power is minimum. For example, the power receiving device may disconnect the load from the power receiving antenna so that the received power is not supplied to the load (such as a charging circuit or battery). This state may be called a Light Load state. At this time, the power transmitting device can recognize that the power loss between the power transmitting device and the power receiving device when transmitting Pt1 as transmitted power is Pt1-Pr1 (Ploss1). Next, the power transmitting device receives from the power receiving device the value of the received power value Pr2 (called Connected Load) received by the power receiving device. At this time, the power receiving device supplies the received power to the load. The power transmitting device then stores the transmitted power value Pt2 at that time (point 1101). Here, the transmitted power value Pt2 or the received power value Pr2 is a predetermined maximum transmitted power or received power. At this time, the power receiving device controls the load so that the received power is the maximum power. For example, the power receiving device connects the receiving antenna to the load so that the received power is supplied to the load. Note that this state may be called a Connected Load state (load connected state). At this time, the power transmitting device can recognize that the power loss between the power transmitting device and the power receiving device when transmitting Pt2 as the transmitted power is Pt2-Pr2 (Ploss2). The power transmitting device then linearly interpolates point 1100 and point 1101 to create line 1102. Line 1102 shows the relationship between transmitted power and received power when there are no foreign objects around the power transmitting device and the power receiving device. Therefore, the power transmitting device can predict the received power when there are no foreign objects from the transmitted power value and line 1102. For example, if the transmitted power value is Pt3, it can be predicted that the received power value will be Pr3 from point 1103 on line 1102 that indicates the transmitted power value Pt3.

[0012] Here, assume that when the power transmitting device transmits power to the power receiving device with a transmission power of Pt3, the power transmitting device receives a received power value Pr3' from the power receiving device. The power transmitting device calculates Pr3-Pr3' (=Ploss_FO) by subtracting the received power value Pr3' actually received from the power receiving device from the received power value Pr3 when the foreign object is not present. This Ploss_FO can be considered to be the power loss consumed by a foreign object if one is present between the power transmitting device and the power receiving device. Therefore, if the power Ploss_FO that would have been consumed by the foreign object is equal to or greater than a predetermined threshold, it is determined that a "foreign object is present" or that a "foreign object may be present."

[0013] Alternatively, the power transmitting device may calculate the power loss Pt3-Pr3 (Ploss3) between the power transmitting device and the power receiving device in advance from the received power value Pr3 when the foreign object is not present. Next, the power loss Pt3-Pr3' (Ploss3') between the power transmitting device and the power receiving device when the foreign object is present may be calculated from the received power value Pr3' received from the power receiving device when the foreign object is present. The power Ploss_FO that would have been consumed by the foreign object may then be calculated by subtracting Ploss3' from Ploss3 (=Ploss_FO).

[0014] As described above, the power Ploss_FO that would have been consumed by a foreign object may be calculated as Pr3 - Pr3' (= Ploss_FO) or as Ploss3' - Ploss3 (= Ploss_FO). In the following description of this specification, the method of calculating Ploss3' - Ploss3 (= Ploss_FO) will be primarily described, but the method of calculating Pr3 - Pr3' (= Ploss_FO) is also applicable. This concludes the explanation of foreign object detection based on the power loss method.

[0015] [Outline of foreign object detection method according to this embodiment] Next, a foreign object detection method in a power transmitting device capable of transmitting power to multiple power receiving devices will be described. Fig. 12 shows an example of the configuration of a wireless power transmission system in this embodiment. Below, the power transmitting device may be referred to as TX and the power receiving device may be referred to as RX. The configurations of TX100 and RX200-220 are shown in Fig. 1 and Fig. 2, respectively, and will be described in detail later.

[0016] The TX 100 transmits power to the RX 200, 210, and 220 placed on the TX 100 (for example, on a charging stand (placing surface) placed close to the power transmitting antennas 105a, 105b, and 105c) via the power transmitting antennas 105a, 105b, and 105c. The RX 200, 210, and 220 each receive the power transmitted from the TX 100 via the power receiving antenna 205. Note that communication between the TX and each RX is also performed via the power transmitting antenna and the power receiving antenna.

[0017] The TX100 shown in Fig. 12(a) has power transmitting antennas 105a to 105b, and transmits power to the RX200 and RX210, for example, as shown in Fig. 12(b). The TX100 shown in Fig. 12(c) has power transmitting antennas 105a to 105c, and transmits power to the RX200 to RX220, for example, as shown in Fig. 12(d), and transmits power to the RX200 and RX210, for example, as shown in Fig. 12(e) and (f).

[0018] Here, let us consider the power loss between each TX and multiple RXs. In a TX that can transmit (charge) power to multiple RXs (for example, a first RX and a second RX), the power loss between the TX and the first RX is different from the power loss between the TX and the second RX. For example, the TX 100 shown in FIG. 12(c) transmits power to the RX 200 via the power transmitting antenna 105a and the power receiving antenna 205 that the RX 200 has. Furthermore, the TX 100 shown in FIG. 12(c) transmits power to the RX 210 via the power transmitting antenna 105b and the power receiving antenna 205 that the RX 210 has. In this case, the power loss between the TX 100 and the RX 200 is different from the power loss between the TX 100 and the RX 210. The reasons for this include the characteristics of the transmitting antenna, the characteristics of the receiving antenna, the relative positions of TX (transmitting antenna) and RX, the effect of RX200 on the electrical characteristics of the transmitting antenna 105b, the effect of RX210 on the electrical characteristics of the transmitting antenna 105a, and the state of the circuit within RX (for example, the connection state between the receiving antenna and the load (such as a charging circuit or battery)).

[0019] For this reason, when a first RX and a second RX are placed on the TX, the power loss between the TX and the first RX may be affected by the second RX. Similarly, the power loss between the TX and the second RX may be affected by the first RX. Therefore, if there is a change in the state of the RXs placed on the TX (number of units, placement position, etc.), the power loss calculated in advance when there is no foreign object between the TX and RX, or the straight line showing the relationship between transmitted power and received power as shown in Figure 11, will also change, resulting in a problem of reduced foreign object detection accuracy.

[0020] To solve this problem, the TX according to this embodiment recalculates the "power loss between the TX and the RX" when it detects that the state of the TX or the RX placed on the TX has changed (a change in the power transmission and reception state within the power transmission range of the TX). Here, an example of the "state of the TX or the RX placed on the TX" is the number of RXs placed on the TX, but is not limited to this. For example, it may be the characteristics of the power transmitting antenna, the characteristics of the power receiving antenna, the positional relationship between the power transmitting device (power transmitting antenna) and the RX, the influence of the RX 200 on the electrical characteristics of the power transmitting antenna 105b, the influence of the RX 210 on the electrical characteristics of the power transmitting antenna 105a, etc. By doing so, when calculating the power loss between TX and RX in advance without a foreign object and when calculating the power loss between TX and RX during power transmission, it is possible to make the same conditions, such as the characteristics of the power transmitting antenna, the characteristics of the power receiving antenna, the positional relationship between TX (power transmitting antenna) and RX, the influence of RX 200 on the electrical characteristics of the power transmitting antenna 105b, the influence of RX 210 on the electrical characteristics of the power transmitting antenna 105a, and the state of the circuit within RX (for example, the connection state of the power receiving antenna and the load (such as a charging circuit or battery)).This makes it possible to properly detect foreign objects in a wireless power transfer system in which TX transmits power to multiple RXs.

[0021] [System Configuration] The wireless power transmission system according to this embodiment shown in FIG. 12 will be described in more detail. The TX100 and the RX200, 210, and 220 comply with the WPC standard. The RX200, 210, and 220 receive power from the TX100 and charge their batteries. The TX100 is an electronic device that wirelessly transmits power to the RX200, 210, and 220 placed on the TX100. The following description will be given using an example in which the RX200, 210, and 220 are placed on the TX100. However, when the TX100 transmits power to the RX200, 210, and 220, the RX200, 210, and 220 do not have to be placed on the TX100 as long as they are within the power transmission range of the TX100.

[0022] The RX200, 210, 220, and TX100 may also have a function for executing applications other than wireless charging. An example of the RX200, 210, and 220 is a smartphone, and an example of the TX100 is an accessory device for charging the smartphone. The RX200, 210, 220, and TX100 may be a tablet, a storage device such as a hard disk drive or a memory device, or an information processing device such as a personal computer (PC). The RX200, 210, 220, and TX100 may be, for example, an image input device such as an imaging device (camera, video camera, etc.) or a scanner, or an image output device such as a printer, copier, or projector. The TX100 may also be a smartphone. In this case, the RX200, 210, and 220 may be another smartphone or wireless earphones. The TX100 may also be a charger installed in a console or the like inside a vehicle.

[0023] This system performs wireless power transmission using an electromagnetic induction method for contactless charging based on the WPC standard. That is, the RX200, 210, 220 and the TX100 perform wireless power transmission for contactless charging based on the WPC standard between the power receiving antenna 205 of the RX200, 210, 220 and the power transmitting antennas 105a to 105c of the TX100. Note that the wireless power transmission method (contactless power transmission method) applied to this system is not limited to the method specified by the WPC standard, and may be other methods such as electromagnetic induction, magnetic field resonance, electric field resonance, microwave, or laser. Furthermore, in this embodiment, wireless power transmission is used for contactless charging, but wireless power transmission may also be performed for purposes other than contactless charging.

[0024] Here, power transmission control according to the WPC standard will be described using an example in which the TX100 is the TX and the RX200, 210, and 220 are the RXs. In the WPC standard, the amount of power guaranteed when the RX200, 210, and 220 receive power from the TX100 is specified by a value called Guaranteed Power (hereinafter referred to as "GP"). GP indicates the power value that is guaranteed to be output to the load (e.g., charging circuit, battery, etc.) of the RX200, 210, and 220, even if the positional relationship between the RX200, 210, and 220 and the TX100 changes and the power transmission efficiency between the receiving antenna and the transmitting antenna decreases. For example, if the GP is 5 watts, the TX100 controls power transmission so that it can output 5 watts to the load in the RX200, 210, and 220, even if the positional relationship between the receiving antenna and the transmitting antenna changes and the power transmission efficiency decreases.

[0025] The WPC standard also specifies a method for the TX100 to detect the presence of an object (foreign object) other than the RX unit around the TX100 (near the receiving antenna). More specifically, it specifies a power loss method that detects foreign objects by measuring the difference between the transmitted power of the TX100 and the received power of the RX200, 210, and 220, and a Q-factor measurement method that detects foreign objects by measuring changes in the quality factor (Q-factor) of the transmitting antenna (transmitting coil) of the TX100. Foreign object detection using the power loss method is performed during power transmission (power transmission) (the power transfer phase, described below). Foreign object detection using the Q-factor measurement method is performed before power transmission (the negotiation or renegotiation phase, described below).

[0026] The RX200, 210, 220 and TX100 according to this embodiment communicate for power transmission and reception control based on the WPC standard. The WPC standard defines multiple phases, including a power transfer phase in which power transmission is performed and one or more phases before the actual power transmission, and communication for the necessary power transmission and reception control is performed in each phase. Phases before power transmission may include a selection phase, a ping phase, an identification and configuration phase, a negotiation phase, and a calibration phase. Note that the identification and configuration phase will be referred to as the I&C phase below.

[0027] In the Selection phase, the TX100 transmits Analog Pings intermittently to detect that an object has been placed on the TX100 (for example, that the RX200, 210, 220 or a piece of conductor has been placed on the charging stand of the TX100). The TX100 detects at least one of the voltage and current values ​​of the power transmitting antenna when the Analog Ping is transmitted, and if the voltage value is below a certain threshold or the current value exceeds a certain threshold, it determines that an object is present and transitions to the Ping phase.

[0028] In the Ping phase, the TX100 transmits a Digital Ping with greater power than the Analog Ping. The power of the Digital Ping is sufficient to activate the control units 201 (Fig. 2) of the RX200, 210, and 220 placed on the TX100. The RX200, 210, and 220 notify the TX100 of the magnitude of the received voltage. In this way, the TX100 recognizes that the object detected in the Selection phase is the RX200, 210, or 220 by receiving a response from the RX200, 210, or 220 that received the Digital Ping. When the TX100 is notified of the received voltage value, it transitions to the I&C phase.

[0029] In the I&C phase, the TX100 identifies the RX200, 210, and 220 and acquires device configuration information (capability information) from the RX200, 210, and 220. To do this, the RX200, 210, and 220 transmit an ID packet and a configuration packet to the TX100. The ID packet contains the identification information of the RX200, 210, and 220, and the configuration packet contains the device configuration information (capability information) of the RX200, 210, and 220. Upon receiving the ID packet and configuration packet, the TX100 responds with an acknowledgement (ACK, positive response). Then the I&C phase ends.

[0030] In the Negotiation phase, the GP value is determined based on the GP value requested by the RX200, 210, and 220, the power transmission capability of the TX100, and other factors. The TX100 also performs foreign object detection processing using the Q-factor measurement method in accordance with requests from the RX200, 210, and 220. The WPC standard also specifies a method in which, after transitioning to the Power Transfer phase, processing similar to that of the Negotiation phase is performed again at the request of the RX. The phase in which these processing steps are performed after transitioning from the Power Transfer phase is called the Renegotiation phase.

[0031] In the calibration phase, the RX200, 210, and 220 notify the TX100 of a predetermined received power value (received power value under light load / received power value under maximum load) based on the WPC standard, and the TX100 performs adjustments to transmit power efficiently. The received power value notified to the TX100 can be used for foreign object detection processing using the power loss method.

[0032] In the Power Transfer phase, control is performed to start and continue power transmission, and to stop power transmission due to an error or full charge. To control power transmission and reception, the TX100 and RX200, 210, and 220 use the same power transmitting antenna (power transmitting coil) and power receiving antenna (power receiving coil) as those used when transmitting wireless power based on the WPC standard, and communicate by superimposing a signal on the electromagnetic waves transmitted from the power transmitting antenna or power receiving antenna. The range in which communication based on the WPC standard is possible between the TX100 and RX200, 210, and 220 is approximately the same as the power transmission range of the TX100.

[0033] [Configuration of power transmission device and power receiving device] Next, the configurations of a power transmitting device and a power receiving device according to this embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a block diagram showing an example of the configuration of a TX (power transmitting device) 100 according to this embodiment. FIG. 2 is a block diagram showing an example of the configuration of an RX (power receiving device) 200 according to this embodiment. Note that the RX 210 and the RX 220 have the same configuration as the RX 200. Note that the configuration described below is merely an example, and part (or in some cases the entirety) of the described configuration may be replaced with another configuration that performs a similar function or may be omitted, or additional configuration may be added to the described configuration. Furthermore, one block described below may be divided into multiple blocks, or multiple blocks may be integrated into one block. Furthermore, although the functions of each functional block described below are implemented as a software program, some or all of the components included in this functional block may be implemented in hardware.

[0034] First, the TX 100 (Fig. 1) will be described. As shown in Fig. 1, the TX 100 has a control unit 101, a power supply unit 102, a power transmission unit 103, a communication unit 104, power transmission antennas 105a to 105c, a memory 106, and an antenna switching unit 107. In Fig. 1, the control unit 101, the power supply unit 102, the power transmission unit 103, the communication unit 104, the memory 106, and the antenna switching unit 107 are depicted as separate entities, but any two or more of these functional blocks may be implemented on the same chip.

[0035] The control unit 101 controls the entire TX 100 by executing a control program stored in the memory 106, for example. The control unit 101 also controls power transmission control, including communication for device authentication in the TX 100. The control unit 101 may also control the execution of applications other than wireless power transmission. The control unit 101 includes one or more processors, such as a CPU (Central Processing Unit) or an MPU (Microprocessor Unit). The control unit 101 may also be configured with dedicated hardware for specific processing, such as an application-specific integrated circuit (ASIC). The control unit 101 may also be configured with an array circuit, such as an FPGA (Field Programmable Gate Array) compiled to execute a specific process. The control unit 101 stores information to be stored during the execution of various processes in the memory 106. The control unit 101 may also measure time using a timer (not shown).

[0036] The power supply unit 102 supplies power to each functional block. The power supply unit 102 is, for example, a commercial power supply or a battery. The battery stores power supplied from the commercial power supply.

[0037] The power transmitting unit 103 converts DC or AC power input from the power supply unit 102 into AC frequency power in a frequency band used for wireless power transmission, and inputs the AC frequency power to the power transmitting antennas 105a to 105c to generate electromagnetic waves for receiving power at the RX. For example, the power transmitting unit 103 converts the DC voltage supplied by the power supply unit 102 into an AC voltage using a switching circuit with a half-bridge or full-bridge configuration using FETs (Field Effect Transistors). In this case, the power transmitting unit 103 includes a gate driver that controls the ON / OFF of the FETs.

[0038] Under the control of the control unit 101, the power transmitting unit 103 adjusts the voltage (power transmission voltage) or current (power transmission current), or both, input to the power transmitting antennas 105a to 105c, thereby controlling the intensity of the electromagnetic waves to be output. Increasing the power transmission voltage or power transmission current increases the intensity of the electromagnetic waves, while decreasing the power transmission voltage or power transmission current decreases the intensity of the electromagnetic waves. Based on instructions from the control unit 101, the power transmitting unit 103 controls the output of AC frequency power so as to start or stop power transmission from the power transmitting antennas 105a to 105c. The power transmitting unit 103 is also assumed to be capable of supplying 15 watts (W) of power to a charging unit of the RX (charging unit 206 (FIG. 2) in the case of the RX200 to 220) that complies with the WPC standard.

[0039] The communication unit 104, under the control of the control unit 101, performs communication with the RX for power transmission control based on the WPC standard as described above. The communication unit 104 modulates electromagnetic waves output from the power transmitting antennas 105a to 105c and transmits information to the RX to perform communication. The communication unit 104 also acquires information transmitted by the RX by demodulating the electromagnetic waves output from the power transmitting antennas 105a to 105c and modulated by the RX. That is, the communication performed by the communication unit 104 is performed by superimposing a signal on the electromagnetic waves transmitted from the power transmitting antennas 105a to 105c. The communication unit 104 may also communicate with the RX using antennas other than the power transmitting antennas 105a to 105c according to a standard other than the WPC standard, or may selectively use multiple communication methods to communicate with the RX.

[0040] The memory 106 can store the control program as well as the status of the TX 100 and RX (received power value, etc.). For example, the status of the TX 100 is acquired by the control unit 101, and the status of the RX is acquired by the RX control unit (in the case of the RX 200 to 220, the control unit 201 (FIG. 2)), and can be received via the communication unit 104.

[0041] A plurality of power transmitting antennas (coils) 105a to 105c are connected to the antenna switching unit 107. The antenna switching unit 107 selects and switches one or more of the plurality of antennas (coils). Although three power transmitting antennas 105a to 105c are shown in FIG. 1, the number of power transmitting coils is not limited to this number. In the following description, the power transmitting antennas 105a to 105c may be collectively referred to as power transmitting antenna 105.

[0042] Next, the RX200 (FIG. 2) will be described. As described above, the RX210 and RX220 have the same configuration as the RX200. As shown in FIG. 2, the RX200 has a control unit 201, a UI (user interface) unit 202, a power receiving unit 203, a communication unit 204, a power receiving antenna 205, a charging unit 206, a battery 207, a memory 208, and a switch unit 209. Note that the multiple functional blocks shown in FIG. 2 may be implemented as a single hardware module.

[0043] The control unit 201 controls the entire RX200 by executing a control program stored in the memory 208, for example. That is, the control unit 201 controls each functional unit shown in FIG. 2. Furthermore, the control unit 201 may perform control for executing applications other than wireless power transmission. An example of the control unit 201 is configured to include one or more processors such as a CPU or an MPU. Note that the control unit 201 may control the entire RX200 (or the entire smartphone if the RX200 is a smartphone) in cooperation with an OS (Operating System) being executed.

[0044] The control unit 201 may also be configured with hardware dedicated to a specific process, such as an ASIC. The control unit 201 may also be configured to include an array circuit, such as an FPGA, compiled to execute a predetermined process. The control unit 201 stores information to be stored while executing various processes in the memory 208. The control unit 201 may also measure time using a timer (not shown).

[0045] The UI unit 202 performs various outputs to the user. The various outputs referred to here include screen display, LED blinking and color changes, audio output from a speaker, vibration of the RX200 main unit, etc. The UI unit 202 is realized by an LCD panel, speaker, vibration motor, etc.

[0046] The power receiving unit 203 acquires, at the power receiving antenna 205, AC power (AC voltage and AC current) generated by electromagnetic induction caused by electromagnetic waves radiated from the power transmitting antenna 105 of the TX100. The power receiving unit 203 then converts the AC power into DC or AC power of a predetermined frequency and outputs the power to the charging unit 206, which performs processing to charge the battery 207. That is, the power receiving unit 203 supplies power to the load in the RX200. The above-mentioned GP is power guaranteed to be output from the power receiving unit 203. The power receiving unit 203 supplies power for the charging unit 206 to charge the battery 207 and is capable of supplying enough power to output 15 watts of power to the charging unit 206. The switch unit 209 controls whether the received power is supplied to the battery (load). When the switch unit 209 connects the charging unit 206 and the battery 207, the received power is supplied to the battery 207. When the switch unit 209 disconnects the charging unit 206 from the battery 207, the received power is not supplied to the battery 207. Although the switch unit 209 is disposed between the charging unit 206 and the battery 207 in FIG. 2 , it may be disposed between the power receiving unit 203 and the charging unit 206. Alternatively, although the switch unit 209 is illustrated as a single block in FIG. 2 , the switch unit may be realized as part of the charging unit 206. The communication unit 204 communicates with the communication unit 104 of the TX100 for power reception control based on the WPC standard as described above. The communication unit 204 demodulates the electromagnetic waves input from the power receiving antenna 205 to acquire information transmitted from the TX100. The communication unit 204 then performs load modulation on the input electromagnetic waves to superimpose a signal related to information to be transmitted to the TX100 onto the electromagnetic waves, thereby communicating with the TX100. The communication unit 204 may communicate with the TX100 using an antenna different from the power receiving antenna 205 and a standard different from the WPC standard, or may selectively use multiple communication methods to communicate with the TX100.

[0047] The memory 208 stores the control program and also stores the status of the TX100 and RX200. For example, the status of the RX200 is acquired by the control unit 201, and the status of the TX100 is acquired by the control unit 101 of the TX100 and can be received via the communication unit 204.

[0048] [Functional configuration of the power transmission device control unit] Next, the functional configuration of the control unit 101 of the TX (power transmitting device) 100 according to this embodiment will be described with reference to Fig. 3. Fig. 3 is a block diagram showing an example of the functional configuration of the control unit 101. The control unit 101 has a communication control unit 301, a power transmission control unit 302, a foreign object detection unit 303, a calculation unit 304, and a determination unit 305.

[0049] The communication control unit 301 is a processing unit that performs control communication with the RX based on the WPC standard via the communication unit 104. The power transmission control unit 302 is a processing unit that controls the power transmission unit 103 and controls power transmission to the RX. The foreign object detection unit 303 is a processing unit that detects foreign objects by measuring the transmission power of the power transmission unit 103 and the Q value of the power transmission antenna 105. The foreign object detection unit 303 can realize a foreign object detection function using a power loss method and a foreign object detection function using a Q value measurement method. The foreign object detection unit 303 may also perform foreign object detection processing using other methods. For example, in a TX equipped with an NFC (Near Field Communication) communication function, the foreign object detection unit 303 may perform foreign object detection processing using an opposing device detection function based on the NFC standard. In addition to detecting foreign objects, the foreign object detection unit 303 can also detect changes in the state of the TX 100. For example, it is possible to detect an increase or decrease in the number of RXs on the TX 100. The calculation unit 304 measures the power output to the RX via the power transmission unit 103 and calculates the average output power value per unit time. The foreign object detection unit 303 performs foreign object detection processing using a power loss method based on the calculation result by the calculation unit 304 and received power information received from the RX via the communication control unit 301. The determination unit 305 determines whether to re-derive calibration data. The determination unit 305 also determines whether the power transmitting antenna currently transmitting power is an antenna for which calibration data is to be re-derived. Calibration data will be described later.

[0050] The functions of the communication control unit 301, power transmission control unit 302, foreign object detection unit 303, calculation unit 304, and determination unit 305 are realized as programs that run in the control unit 101. Each processing unit is configured as an independent program, and can run in parallel while maintaining synchronization between the programs through event processing or the like.

[0051] [Processing flow by power transmission device] Next, the flow of processing executed by the TX100 will be described. FIG. 4 shows a flowchart of the processing executed by the TX100. This processing can be implemented, for example, by the control unit 101 of the TX100 executing a program read from the memory 106. At least a part of the following procedure can be implemented by hardware. In this case, the hardware can be implemented, for example, by using a predetermined compiler to automatically generate a dedicated circuit using a gate array circuit such as an FPGA from a program for implementing each processing step. This processing can also be executed when the TX100 is powered on, when the user of the TX100 inputs an instruction to start a contactless charging application, or when the TX100 is connected to a commercial power source and receives power. This processing can also be started by some other trigger. The TX100 executes this processing using multiple power transmitting antennas 105. The TX100 may sequentially select and execute one of the antennas, or may execute the processing in parallel using multiple or all of the power transmitting antennas.

[0052] In the following description, it is assumed that one or more RXs are placed on the TX100 (for example, on a charging stand (placing surface) configured to be close to multiple power transmission antennas on the TX100), but it is also possible to assume that they are present within the power transmission range of the TX100.

[0053] First, the communication control unit 301 of the TX 100 executes the processes of the Selection phase and Ping phase, and waits for an object to be placed on the TX 100 (S401). The foreign object detection unit 303 of the TX 100 detects that the placed object is an RX through communication via the communication control unit 301 (S402). Here, the foreign object detection unit 303 identifies the power transmitting antenna 105 that detected the RX, and acquires information about the identified power transmitting antenna 105 and information about the number of RXs (for example, the number of identified power transmitting antennas 105). The information about the power transmitting antenna may include, but is not limited to, identification information (identifier) ​​of the power transmitting antenna and position information of the power transmitting antenna. The communication control unit 301 stores the acquired information in the memory 106.

[0054] Next, the TX 100 transitions to the I&C phase, and the communication control unit 301 acquires the identification information and capability information of the RX (S403). Here, the identification information of the RX may include a Manufacturer Code and a Basic Device ID of the WPC standard. The capability information of the RX may include an information element capable of identifying the version of the WPC standard supported, a Maximum Power Value that specifies the maximum power that the RX can supply to a load, and information indicating whether the RX has a negotiation function of the WPC standard. Note that these are merely examples, and the identification information and capability information of the RX may be replaced by other information, or may include other information in addition to the above information. For example, the identification information may be any other identification information capable of identifying an individual RX, such as a Wireless Power ID. Furthermore, the TX 100 may acquire the identification information and capability information of the RX by a method other than communication in the I&C phase. The communication control unit 301 stores the acquired identification information and capability information of the RX in the memory 106.

[0055] Next, the communication control unit 301 of the TX 100 executes the negotiation phase process and determines the GP value based on the request from the RX (S404). Note that in S404, other procedures for determining the GP may be executed, not limited to the negotiation phase communication. Furthermore, if the TX 100 acquires information indicating that the RX does not support the negotiation phase (for example, in S403), it may not execute the negotiation phase communication and may set the GP value to a small value (for example, specified in advance in the WPC standard).

[0056] After determining the GP, the communication control unit 301 of the TX 100 executes the calibration phase based on the determined GP (S405). In the calibration phase, the TX 100 derives the relationship between the transmitted power and the received power in a state where there is no foreign object, as described above with reference to FIG. 11. Specifically, the foreign object detection unit 303 of the TX 100 derives data indicating the power loss between the TX and RX in a state where there is no foreign object (power loss data) based on the WPC standard, using a predetermined received power value (including the received power value in a light load state / light load and the received power value in a maximum load / connected load state) acquired from the RX. (This corresponds to the line 1102 in FIG. 11.) Hereinafter, this power loss data will be referred to as calibration data. This calibration data can be used for foreign object detection processing using the power loss method. Foreign object detection based on the power loss method has been described above. In other words, if the power loss between TX and RX during power transmission, calculated based on the calibration data and the received power value at RX received during power transmission, is equal to or greater than a predetermined threshold, TX determines that "foreign object is present" or "there is a possibility that a foreign object exists."

[0057] After the communication control unit 301 of the TX100 derives the calibration data, the power transmission control unit 302 starts power transmission (S406). Power transmission is performed by processing in the Power Transfer phase. However, this is not limited to this, and power transmission may be performed by methods other than the WPC standard. When the TX100 starts power transmission, it executes power transmission control processing (S407). This power transmission control processing will be described later. When the power transmission control unit 302 of the TX100 ends the power transmission control processing, the foreign object detection unit 303 confirms that an RX is not placed on the TX100 (S408). For example, the foreign object detection unit 303 confirms, through communication via the communication control unit 301, that an RX is not placed on the TX100 and that there is no power transmitting antenna 105 detecting the RX. Then, the processing returns to the selection phase of S401. When the TX100 receives an End Power Transfer of the WPC standard from the RX via the communication control unit 301, the TX100 ends the processing in any processing phase in accordance with the WPC standard, stops power transmission, and returns to S401. When the battery is fully charged, the RX also sends an End Power Transfer, and the processing returns to S401.

[0058] (Flow of power transmission control process (S407)) Next, an example of the flow of the power transmission control process executed by the TX100 in S407 of FIG. 4 will be described with reference to FIG. 5. FIG. 5 is an exemplary flowchart of the power transmission control process. This process can be realized, for example, by the control unit 101 of the TX100 executing a program read from the memory 106. Note that at least a part of the following procedure may be realized by hardware. In this case, the hardware can be realized, for example, by using a predetermined compiler to automatically generate a dedicated circuit using a gate array circuit such as an FPGA from a program for implementing each processing step.

[0059] In the following description, the power transmitting antenna transmitting power in S406 of Fig. 4 is referred to as the target power transmitting antenna. First, the foreign object detection unit 303 of the TX 100 determines whether or not there has been a change in the number of RXs placed on the TX 100 (near the target power transmitting antenna) (S501). For example, the foreign object detection unit 303 determines whether or not there has been a change in the number of RXs placed on the TX 100 (addition or removal of other RXs) based on information regarding the presence / number of RXs placed on the TX 100 acquired in S402 and S408. Note that this is not a limitation, and the foreign object detection unit 303 may make the determination based on, for example, the number of RXs executing the processing of the power transfer phase. If it is determined that there has been a change in the number of RXs (YES in S501), the process proceeds to S502. If it is determined that there has been no change in the number of RXs (NO in S501), the process proceeds to S503.

[0060] In S502, the determination unit 305 of the TX 100 determines whether to re-derive calibration data for the target power transmitting antenna (calibration data re-derivation determination process). The calibration data re-derivation determination process is a process for determining whether or not calibration data should be re-derived. The calibration data re-derivation determination process will be described later with reference to FIG. 6.

[0061] In S503, the determination unit 305 of the TX 100 determines whether or not to start re-deriving calibration data for the target power transmitting antenna based on the processing of S502. For example, the determination unit 305 determines to start re-derivation when a predetermined received power value (a received power value in a low-load state) is notified from the RX via the communication control unit 301, but the determination unit 305 is not limited to this. For example, the determination unit 305 may determine to start re-derivation when a predetermined notification for starting the calibration phase is received from the RX via the communication control unit 301. Furthermore, the determination unit 305 may determine to start re-derivation in response to transmitting a calibration data re-derivation notification to the RX via the communication control unit 301. If it is determined to start re-derivation of calibration data (YES in S503), the communication control unit 301 derives calibration data, i.e., executes processing of the calibration phase (S504), and the processing proceeds to S505. On the other hand, if it is determined that the re-derivation of the calibration data should not be started (NO in S503), the process proceeds to S505.

[0062] In S505, the communication control unit 301 of the TX100 determines whether or not a transmission power output change instruction has been received. Here, the transmission power output change instruction is issued by including a Control Error Value, which is a value indicating the amount of change in voltage, in a Control Error message of the WPC standard. The Control Error Value stores a positive value if the transmission power output is to be increased, a negative value if the transmission power output is to be decreased, and 0 if the transmission power output is not to be changed. If a transmission power output change instruction has been received (YES in S505), the power transmission control unit 302 changes the transmission power output based on the instructed amount of change (S506), and the process proceeds to S507. On the other hand, if a transmission power output change instruction has not been received (NO in S505), the power transmission control unit 302 does nothing and the process proceeds to S507.

[0063] In S507, the communication control unit 301 of the TX 100 determines whether or not a received power value has been received from the RX. Here, the received power value is the value of the received power that is actually being received at that time in the RX. Note that the received power value is transmitted and received using a Received Power (mode 0) message defined in the WPC standard, but is not limited to this. Note that the received power value may be received multiple times. If one or more received power values ​​have been received (YES in S507), the process proceeds to S508, and if no received power value has been received (NO in S507), the process proceeds to S515.

[0064] In S508, the foreign object detection unit 303 of the TX100 calculates the power loss difference for foreign object detection using the power loss method (the difference between the received power value when no foreign object is present and the received power value received from the RX during power transmission (see the explanation of FIG. 11)). Then, the foreign object detection unit 303 determines whether the difference is greater than or equal to a threshold (S509). If the power loss difference is greater than or equal to the threshold (YES in S509), the process proceeds to S510, and if the power loss difference is less than the threshold (NO in S509), the process proceeds to S511.

[0065] In S510, the determination unit 305 of the TX 100 determines whether the target power transmitting antenna is an antenna for which calibration data is to be re-derived, that is, whether the target power transmitting antenna is an antenna for which calibration data is determined to be re-derived in S502. If the target power transmitting antenna is a re-derivation target (YES in S510), the foreign object detection unit 303 stores the power loss calculated in S508 and the received power value received from the RX during power transmission in the memory 106 (S511). Note that the received power value received from the RX acquired in S508 and stored in S511 may be a time average or median of the multiple received power values ​​received in S507.

[0066] Thereafter, the communication control unit 301 transmits an acceptance response to RX (S512), and the process proceeds to S515. On the other hand, if the target power transmitting antenna is not a re-derivation target (NO in S510), the foreign object detection unit 303 determines that "foreign object is present" or "there is a possibility that a foreign object exists" (S513). Thereafter, the communication control unit 301 transmits a rejection response to RX (S514), and the process proceeds to S515.

[0067] In this way, even if the difference in power loss for foreign object detection using the power loss method exceeds the threshold, the TX100 does not determine that a "foreign object is present" or that a "foreign object may be present" if the antenna to which power is being transmitted is the target for re-deriving calibration data. This makes it possible to prevent false detection of a foreign object, i.e., unnecessary power transmission stoppages and reductions in power transmission efficiency, when the state of the TX changes.

[0068] Note that a second threshold different from the aforementioned threshold may be set, and when the difference in power loss for detecting a foreign object is equal to or greater than the second threshold, the foreign object detection unit 303 may determine that a "foreign object is present" or that a "foreign object may exist." For example, by setting the second threshold to a value greater than the maximum difference in power loss expected as an effect of a power transmitting antenna adjacent to the power transmitting target antenna, a foreign object can be detected even if a foreign object is introduced when another power receiving device is placed or removed.

[0069] In S515, the power transmission control unit 302 of the TX100 determines whether to stop power transmission. Here, the determination of whether to stop power transmission is made based on whether it was determined in S513 that "foreign object is present" or "there is a possibility that a foreign object is present," but is not limited to this. For example, the power transmission control unit 302 may determine to stop power transmission when it receives an End Power Transfer via the communication control unit 301, or may determine to stop power transmission when it detects an abnormality due to heat generation or the like of the TX100 itself. If the power transmission control unit 302 of the TX100 determines to stop power transmission (YES in S515), it stops power transmission (S516) and ends this processing. On the other hand, if the power transmission control unit 302 determines not to stop power transmission, i.e., to continue power transmission (NO in S515), the processing returns to S501. In S504, the calibration data for the target power transmitting antenna can be derived while power is being transmitted via other power transmitting antennas. This makes it possible to derive calibration data that includes the influence of other RXs on the electrical characteristics of the target power transmitting antenna and the influence of the power transmitting RX on the electrical characteristics of the power transmitting antennas of other RXs.

[0070] 5, the process may be configured to proceed to S502 if a change in the power transmission and reception state within the power transmission range of the TX (such as the characteristics of the power transmitting antenna and power receiving antenna, the positional relationship between the TX (power transmitting antenna) and the RX, the influence of another RX on the electrical characteristics of the antenna to which power is being transmitted, or the influence of the RX transmitting power on the electrical characteristics of the power transmitting antenna of another RX) is detected in S501. Also, the process may be configured to omit S502 and S503 and proceed to S504 if the answer to S501 is Yes.

[0071] [Calibration data re-derivation judgment process] Next, an example of the flow of the calibration data rederivation determination process executed by the TX100 in S502 will be described with reference to Figure 6. Figure 6 is an exemplary flowchart of the calibration data rederivation determination process. This process can be implemented, for example, by the control unit 101 of the TX100 executing a program read from the memory 106. Note that at least part of the following procedure may be implemented by hardware. In this case, the hardware can be implemented, for example, by using a predetermined compiler to automatically generate a dedicated circuit using a gate array circuit such as an FPGA from a program for implementing each processing step.

[0072] When the process starts, the determination unit 305 of the TX 100 determines whether a change in the power transmission and reception state within the power transmission range of the TX 100 will affect foreign object detection by the target power transmitting antenna. For example, the determination unit 305 determines whether a power transmitting antenna that is affected by a change in the number of mounted RXs, i.e., another power transmitting antenna that transmits power to a mounted / removed RX, affects foreign object detection by the target power transmitting antenna. This determination can be made based on power transmitting antenna information stored in advance, such as that shown in FIG. 10. FIG. 10 shows an example of power transmitting antenna (power transmitting coil) information stored by the TX 100. FIG. 10 shows an example of the relationship between the target power transmitting antenna and adjacent power transmitting antennas when power transmitting antennas 105a to 105c are arranged as shown in FIG. 12(c). Here, it is assumed that the adjacent power transmitting antenna is determined to affect foreign object detection by the target power transmitting antenna, but this is not limited to this. For example, TX100 may store the position information of each power transmitting antenna in advance, calculate the distance between the target power transmitting antenna and other power transmitting antennas that transmit power to other RXs that have been placed / removed, and determine that there is an impact if the distance is within a threshold value.

[0073] If the determination unit 305 of the TX100 determines that the foreign object detection of the processing transmitting antenna is affected (YES in S601), the process proceeds to S602. If the determination unit 305 determines that there is no effect (NO in S601), the process determines that re-deriving the calibration data is unnecessary and ends this process. In S602, the determination unit 305 of the TX100 determines whether the GP determined as RX on the target transmitting antenna is equal to or greater than a threshold. If the GP is equal to or greater than the threshold (YES in S602), the process proceeds to S603. If the GP is less than the threshold (NO in S602), the determination unit 305 determines that re-deriving the calibration data is unnecessary and ends this process. Note that the determination of whether the GP is equal to or greater than the threshold may be made based on the GP determined on a transmitting antenna on which another RX is mounted, but is not limited to this.

[0074] In S603, the determination unit 305 of the TX 100 determines whether or not a received power value has been received from the RX via the communication control unit 301. If a received power value has been received (YES in S603), the process proceeds to S604. If a received power value has not been received (NO in S603), the process of S603 is repeated until a received power value is received. Note that received power values ​​may be received multiple times. When one or more received power values ​​have been received from the RX, the determination unit 305 calculates the difference between the received power value during power transmission acquired in S508 and stored in S511 and the received power value received in S603 as the difference in power loss during power transmission (S604). Then, the determination unit 305 determines whether the difference is equal to or greater than a reference value (S605). In this way, the determination unit 305 can actually measure the change in power loss before and after placing or removing another RX, that is, determine whether or not foreign object detection in the target power transmitting antenna is actually affected.

[0075] The two received power values ​​used to calculate the power loss may be the time average or median of the multiple received power values ​​received in S505 and S603. This makes it possible to relatively stably determine whether or not the target transmitting antenna is actually affected by foreign object detection, even in situations where the received power value fluctuates due to the operating state of the RX, its position, etc.

[0076] If the difference in power loss is equal to or greater than the reference value (YES in S605), the determination unit 305 sets the target power transmitting antenna as a target for re-deriving calibration data and stores the result in the memory 106 (S606). After that, the determination unit 305 transmits a calibration data re-derivation notification to the RX via the communication control unit 301 (S607), and ends this process. Here, the calibration data re-derivation notification is transmitted as a response to the notification of the received power value, including the reason for the re-derivation, but this is not limited to this. For example, the calibration data re-derivation notification may be transmitted separately as a separate message after transmitting the response to the notification of the received power value, or may be transmitted as a response to another message received from the power receiving device.

[0077] In this way, if another RX is placed or removed while transmitting power to the RX (and other RXs), affecting foreign object detection, the TX100 can reliably re-derive the calibration data by notifying the RX to re-derive the calibration data. This makes it possible to prevent erroneous foreign object detection, i.e., unnecessary power transmission stoppages and reductions in power transmission efficiency. On the other hand, if the difference is less than the reference value (NO in S605), the TX100 sends an acceptance response to the RX (S608), and concludes that re-deriving the calibration data is not necessary, thereby ending this process. In the process shown in FIG. 6, steps S601 and S602 may be omitted, and the process may start from step S603.

[0078] As described above, when the placement or removal of another RX affects foreign object detection during power transmission, unnecessary power transmission stoppages and reductions in power transmission efficiency due to erroneous foreign object detection can be prevented by re-deriving calibration data. On the other hand, even when another RX is placed or removed, if it is determined that there is no or sufficiently small impact on foreign object detection during power transmission based on changes in the position of the power transmitting antenna, GP, and actual power loss, calibration data is not re-derived. This prevents the execution of unnecessary calibration phase processing, such as control of power transmission output to change the received power value in the RX, and allows high-speed power transmission to continue at a relatively high power transmission output.

[0079] [Processing flow executed by the system] Next, the processing flow of the TX 100 described with reference to FIGS. 4 to 6 will be described assuming several situations. It is assumed that, in the initial state, no RX is placed on the TX 100, and the TX 100 has sufficient power transmission capability to perform power transmission at the GP requested by the RX. It is also assumed that a reference value for the difference in power loss (difference in received power value) between before and after another RX is placed, and a threshold value for the difference in power loss for foreign object detection using the power loss method during power transmission (the difference between the received power value when no foreign object is present and the received power value received from the RX during power transmission (see the description of FIG. 11)) are set in advance in the TX 100 as predetermined values. The reference value and threshold value may be set by a user's input operation, etc. In the processing examples shown below, the reference value is 100 mW, and the threshold value is 750 mW, but are not limited to this. For example, the respective values ​​may be the same, or the threshold value may be set to be greater than the reference value. In addition, in the following description, the expression "RX is placed on the power transmitting antennas 105a to 105c of TX100" is synonymous with "RX is placed on a charging stand (placing surface) configured in close proximity to the power transmitting antennas 105a to 105c" or "RX is placed in the vicinity (power transmission range) of the power transmitting antennas 105a to 105c."

[0080] <First processing example> First, a first processing example will be described. In this processing example, the TX100 has power transmitting antennas 105a to 105c as a system configuration, as shown in Fig. 12(c). When the TX100 starts processing, the RX200 is placed on the power transmitting antenna 105a of the TX100, and power transmission begins after deriving calibration data. Then, after the TX100 starts transmitting power to the RX200, the RX210 is placed on the power transmitting antenna 105b of the TX100. Here, as shown in Fig. 12(e), the power transmitting antenna 105b on which the RX210 is placed is adjacent to the power transmitting antenna 105a on which the RX200 is placed. Furthermore, because the difference in power loss (difference in received power value) before and after placing the RX210 on the power transmitting antenna 105a is equal to or greater than a predetermined reference value, the TX100 determines that foreign object detection is affected and makes the power transmitting antenna 105a a target for re-deriving calibration data. After that, although the difference in power loss for foreign object detection using the power loss method is equal to or greater than a predetermined threshold, the TX100 does not determine that a foreign object has been detected and performs the processing of the calibration phase again because the power transmitting antenna 105a is a target for re-deriving calibration data.

[0081] 7 shows the operation sequence in the first processing example. The TX100 waits for an object to be placed on the power transmitting antenna 105a by Analog Ping (S401, F701). When the RX200 is placed, a change occurs in the Analog Ping, and the TX100 detects that an object has been placed (F702, F703, F704). The RX200 detects that the RX200 itself has been placed on the TX100 (near the power transmitting antenna 105a) by the subsequent Digital Ping (F705, F706). Furthermore, the TX100 detects that the placed object is the RX (RX200) by the response to the Digital Ping (S402). Subsequently, the TX100 acquires identification information and capability information from the RX200 by communication in the I&C phase (S403, F707). Next, the TX100 and the RX200 execute communication in the negotiation phase, and it is assumed that GP=15W is determined (S404, F708).

[0082] Next, the TX100 and the RX200 start communication in the calibration phase and derive calibration data for the power transmitting antenna 105a (S405). After that, the TX100 starts transmitting power to the RX200 and performs power transmission control processing (S406, S407). Here, since there is no change in the number of RXs placed on the other power transmitting antennas 105b and 105c, the calibration data is not re-derived (NO in S501, NO in S503). When the TX100 receives a power transmission output change instruction from the RX200 instructing not to change the power transmission output, the TX100 does not change the power transmission output in accordance with the instruction (YES in S505, S506, F710). Next, the TX100 receives a notification from the RX200 that the received power value is 15 W, and calculates the difference in power loss for foreign object detection using the power loss method (YES in S507, S508, F711, F712). In this case, there is no change in the number of RXs placed or the presence of foreign objects, and the difference in power loss is less than the threshold, so the TX100 stores the received power value and sends an ACK (NO in S509, S511, S512, F713, F714).

[0083] Meanwhile, the TX100 also waits for an object to be placed on the power transmitting antenna 105b by Analog Ping (S401, F715). When the RX210 is placed, a change occurs in the Analog Ping, and the TX100 detects that an object has been placed (F716, F717, F718). The RX210 detects that the RX210 itself has been placed on the TX100 (near the power transmitting antenna 105b) by the subsequent Digital Ping (F719, F720). Furthermore, the TX100 detects that the placed object is the RX (RX210) by the response to the Digital Ping (S402). Subsequently, the TX100 acquires identification information and capability information from the RX210 by communication in the I&C phase (S403, F721). Next, the TX100 and the RX210 execute communication in the negotiation phase, and it is assumed that GP=15W is determined (S404, F722).

[0084] Next, because there is a change in the number of RXs placed, the TX100 starts the calibration data re-derivation determination process in the power transmitting antenna 105a (YES in S501, S502). The TX100 determines that the power transmitting antenna 105b on which the RX210 is placed is adjacent to the power transmitting antenna 105a, and therefore affects foreign object detection (YES in S601). Next, because the GP determined to be that of the RX200 is equal to or greater than the threshold, the TX100 receives a notification from the RX200 that the received power value is 14 W, and calculates the difference in power loss before and after the RX210 was placed (YES in S602, YES in S603, S604, F723, F724). Because the difference in power loss (difference in received power value) (= 1 W) is equal to or greater than the reference value, the TX100 determines that foreign object detection is being affected and targets the power transmitting antenna 105a for re-deriving calibration data (YES in S605, S606, F725). The TX100 then transmits a calibration data re-derivation notification to the RX200 (S607, F726). Next, when the TX100 receives another notification of the received power value (= 14 W) from the RX200, it calculates the power loss difference for foreign object detection using the power loss method (YES in S507, S508, F727, F728). At this time, the TX100 determines that the difference in power loss is equal to or greater than the threshold, but since the calibration data is to be re-derived, it does not determine that a foreign object is present, stores the received power value (=14 W), and sends an ACK (acknowledgment) (YES in S509, YES in S510, S511, S512, F729, F730).Then, the TX100 executes the calibration phase processing for the power transmitting antennas 105a and 105b, and derives the calibration data for each (S405, F731, YES in S503, S504, F732).

[0085] According to the operation described above, when the TX100 starts transmitting power to the RX200 and the RX210 is placed on the TX100, foreign object detection during power transmission to the RX200 is affected, so the TX100 re-derives the calibration data. Furthermore, at this time, the TX100 does not determine that a foreign object is present, even if the difference in power loss for foreign object detection using the power loss method exceeds the range within which it can be determined that no foreign object is present. This makes it possible to prevent unnecessary power transmission interruptions and reductions in power transmission efficiency due to erroneous foreign object detection by the TX100.

[0086] <Processing example 2> Next, a second processing example will be described. In this processing example, the TX100 has power transmitting antennas 105a to 105c as a system configuration, as shown in FIG. 12(c). When the TX100 starts processing, the RX200 is placed on the power transmitting antenna 105a of the TX100, and power transmission begins after deriving calibration data. Then, after the TX100 starts transmitting power to the RX200, the RX210 is placed on the power transmitting antenna 105b of the TX100. Here, as shown in FIG. 12(f), the power transmitting antenna 105c on which the RX210 is placed is not adjacent to the power transmitting antenna 105a on which the RX200 is placed. Therefore, the TX100 determines that there is no effect on foreign object detection, does not select the power transmitting antenna 105a as a target for re-deriving calibration data, and does not re-execute the processing of the calibration phase.

[0087] 8 shows the operation sequence in the second processing example. The processing of F801 to F822 is the same as F701 to F722 in FIG. 7, and therefore a description thereof will be omitted. Because there is a change in the number of mounted RXs, the TX100 starts the calibration data re-derivation determination processing (YES in S501, S502). Because the power transmitting antenna 105c on which the RX210 is mounted is not adjacent to the power transmitting antenna 105a, the TX100 determines that there is no effect on foreign object detection and does not consider it as a target for re-derivation of calibration data (NO in S601, F823). Thereafter, the TX100 receives notification of the received power value (=15 W) from the RX200 and calculates the difference in power loss for foreign object detection using the power loss method (YES in S507, S508, F824, F825). At this time, the TX100 determines that there is no foreign object because the difference in power loss is less than the threshold, stores the received power value (=15 W), and sends an ACK (NO in S509, S511, S512, F826, F827). After that, the TX100 executes the calibration phase process only for the power transmitting antenna 105c, and derives calibration data (S405, F828).

[0088] According to the operation described above, when the RX210 is placed on the TX100 after starting power transmission to the RX200, the TX100 does not re-derive calibration data, determining that the positions of the power transmitting antenna 105a and the power transmitting antenna 105c will not affect power transmission to the RX200. This prevents the TX100 from executing unnecessary calibration phase processing, such as control of the power transmission output to change the received power value in the RX200, and allows high-speed power transmission at a relatively high power transmission output to continue.

[0089] <Processing example 3> Next, a third processing example will be described. In this processing example, the TX100 has power transmitting antennas 105a to 105c as a system configuration, as shown in Fig. 12(c). When the TX100 starts processing, the RX200 is placed on the power transmitting antenna 105a of the TX100, and power transmission is started after deriving calibration data. Then, after the TX100 starts transmitting power to the RX200, the RX210 is placed on the power transmitting antenna 105b of the TX100. Here, as shown in Fig. 12(e), the power transmitting antenna 105b on which the RX210 is placed is adjacent to the power transmitting antenna 105a on which the RX200 is placed. However, since the difference in power loss (difference in received power value) before and after placing the RX210 on the transmitting antenna 105a is less than a predetermined reference value, the TX100 determines that there is no impact on foreign object detection, does not target the transmitting antenna 105a for re-deriving calibration data, and does not perform the calibration phase processing again.

[0090] 9 shows the operation sequence in the third processing example. The processing of F901 to F922 is the same as F701 to F722 in FIG. 7, and therefore a description thereof will be omitted. Because there is a change in the number of RXs placed, the TX100 starts the calibration data re-derivation determination processing (YES in S501, S502). The TX100 determines that the power transmitting antenna 105b on which the RX210 is placed is adjacent to the power transmitting antenna 105a, and therefore affects foreign object detection (YES in S601). After that, because the GP determined between the TX100 and the RX200 is equal to or greater than the threshold, the TX100 receives a notification of the received power value (=15 W) from the RX200 and calculates the difference in power loss (difference in received power value) between before and after the RX210 was placed (S603, S604, F823, F824). Because the difference is less than the reference value, the TX100 determines that there is no impact on foreign object detection and does not target the power transmitting antenna 105a for re-deriving calibration data, and sends an ACK (YES in S605, S606, S607, F825, F826). After that, the TX100 again receives notification of the received power value (= 15 W) from the RX200 and calculates the power loss difference for foreign object detection using the power loss method (YES in S507, S508, F827, F828). At this time, because the power loss difference is less than the threshold, the TX100 determines that there is no foreign object, stores the received power value (= 15 W), and sends an ACK (NO in S509, S511, S512, F829, F830). Thereafter, the TX 100 executes the process of the calibration phase only for the power transmitting antenna 105b, and derives the calibration data (S405, F931).

[0091] According to the operation described above, when the RX210 is placed on the TX100 after starting power transmission to the RX200, the TX100 can determine from the difference in power loss before and after placement (difference in received power value) that there will be no impact on power transmission to the RX200, and therefore does not re-derive calibration data. This prevents the TX100 from executing unnecessary calibration phase processing, such as controlling the transmitted power output to change the received power value in the RX200, and allows high-speed power transmission at a relatively high transmitted power output to continue.

[0092] As described above, according to the embodiment, when there is a change in the state (number of devices, etc.) of the power receiving devices placed on the power transmitting device, the power loss when there is no foreign object between the power transmitting and receiving devices can be recalculated, thereby improving the accuracy of foreign object detection during the power transmission process.

[0093] [Other embodiments] In the above-described embodiment, the case where the TX can input power from one power transmitting unit to all power transmitting antennas has been described. However, the TX may have multiple power transmitting units, and each power transmitting unit may input power to a different group of power transmitting coils. In this case, the determination of whether to re-derive calibration data may be made based on which power transmitting unit the power transmitting antenna on which the RX is placed / removed can input power from. For example, if the power transmitting antenna on which the RX is placed / removed can input power from a power transmitting unit currently transmitting power to another RX, it is determined that this will affect foreign object detection during power transmission to the other RX, and therefore it is determined that the calibration data should be re-derived. On the other hand, if the power transmitting antenna on which the TX is placed / removed cannot input power from a power transmitting unit currently transmitting power to the other RX, it is determined that this will not affect foreign object detection during power transmission to the other RX, and therefore it is determined not to re-derive calibration data. Furthermore, whether or not to re-derive calibration data may be determined based on whether or not the power transmitting antenna on which the RX has been placed / removed can receive power from which power transmitting unit, and also based on whether or not the position of the power transmitting antenna is adjacent to that of another RX. This makes it possible to appropriately determine whether or not to re-derive calibration data even in a TX with multiple power transmitting units, thereby improving the accuracy of foreign object detection during power transmission processing.

[0094] In the above-described embodiment, the determination of whether to re-derive calibration data is made when the number of mounted RXs changes (when another RX is added or removed) but other triggers are also possible. For example, when power transmission in another RX is stopped due to full charge or detection of a foreign object. This makes it possible to improve the accuracy of foreign object detection during power transmission processing by taking into account the influence that the RX that has stopped power transmission has on the electrical characteristics of the power transmission antennas of the other RXs, even when the number of mounted RXs has not changed.

[0095] In the above-described embodiment, the determination of whether or not foreign object detection is affected by power transmission to another RX based on the difference in power loss is performed by determining whether the power transmitting antenna on which the RX is placed / removed and the power transmitting antenna currently transmitting power to the other RX are adjacent to each other. However, this is not limited to this. For example, the determination may be performed by determining whether the power transmitting antenna on which the RX is placed / removed and the power transmitting antenna currently transmitting power to the other RX physically overlap. If they overlap, there is a high probability that the electrical characteristics of the power transmitting antenna currently transmitting power to the other RX, i.e., the foreign object detection, will be affected. Therefore, calibration data is re-derived without performing a determination based on the difference in power loss. This makes it possible to more quickly prevent unnecessary power transmission interruptions and reductions in power transmission efficiency due to erroneous foreign object detection in the TX.

[0096] In the above-described embodiment, when a power transmitting antenna on which an RX has been placed / removed is adjacent to a power transmitting antenna currently transmitting power to another RX, a determination is made as to whether or not to re-derive calibration data based on the difference in power loss. However, power loss is easily affected by factors such as heat generation, and the possibility of an erroneous determination, such as determining that there is no effect on foreign object detection despite the effect, cannot be ruled out. Therefore, a value other than power loss may be used for the determination. For example, the determination may be made based on whether the difference in the Q value (hereinafter referred to as the second Q value) in the time domain, which represents the attenuation state of the transmitted wave before and after the RX is placed, is less than a predetermined reference value. This makes it possible to determine the presence or absence of an effect more accurately, and by recalculating the power loss when there is no foreign object between the power transmitting and receiving devices, it is possible to improve the accuracy of foreign object detection during power transmission processing. Furthermore, the determination may be made using both the power loss and the second Q value. For example, if it is determined that there is no effect based on the difference in power loss, a determination may be made based on the difference in the second Q value. Furthermore, the determination based on the second Q value may be made before the determination based on the power loss, but this is not limited to this. In this way, by combining a plurality of values, it is possible to determine with a higher probability whether or not there is an effect on foreign object detection compared to when a determination is made using a single value. The second Q value may be expressed by the following formula: In a transmission waveform expressed in terms of time and voltage, A1 is the voltage value at time T1, A2 is the voltage value at time T2, and F is the frequency f of the high-frequency voltage. Q=πf(T2-T1) / ln(A1 / A2) (Equation 1) The second Q value may be obtained from the value of the slope of the line calculated from (A1-A2) / (T2-T1). Alternatively, if the observation time is fixed, the second Q value before and after placing the RX may be compared by comparing the value of (A1-A2) representing the difference in voltage values ​​or the value of the voltage value ratio (A1 / A2). Alternatively, if the voltage value A1 when transmitting power is constant, the value of the voltage value A2 after a predetermined time has elapsed may be compared. Alternatively, the value of the time (T2-T1) until the voltage value A1 reaches the predetermined voltage value A2 may be compared. The second Q value may also be obtained based on a power transmission waveform expressed in terms of time and current.

[0097] In the above-described embodiment, the power transmitting device has been described as being configured such that one power transmitting antenna selected from multiple power transmitting antennas is connected to one power transmitting unit. However, multiple power transmitting units may be connected to one power transmitting antenna. That is, when the power transmitting device has a first power transmitting unit (power transmitting circuit) and a second power transmitting unit (power transmitting circuit), and the first power transmitting antenna and the second power transmitting antenna are connected to the first power transmitting antenna, either the first power transmitting unit or the second power transmitting unit may be connected to the first power transmitting antenna. Here, consider a case where the first power transmitting unit (power transmitting circuit) is connected to the first power transmitting antenna and power is being transmitted to the power receiving device, but the power transmitting unit (power transmitting circuit) connected to the first power transmitting antenna is switched from the first power transmitting unit (power transmitting circuit) to the second power transmitting unit (power transmitting circuit). When the electrical characteristics of the first power transmitting unit and the second power transmitting unit are the same, the above-mentioned calibration data does not change, and therefore, it is possible to transmit power from the second power transmitting unit (power transmitting circuit) to the power receiving device using the already acquired calibration data by the method described in the above embodiment. On the other hand, when the electrical characteristics of the first power transmitting unit and the second power transmitting unit are different, the above-mentioned calibration data also changes, and therefore, it is not possible to transmit power using the already acquired calibration data. Therefore, it is possible to derive (acquire) calibration data again by the method described in the above embodiment and transmit power from the second power transmitting unit (power transmitting circuit) to the power receiving device using the calibration data. At this time, the power transmitting device stores in memory information that associates information about the RX to be transmitted, information about the power transmitting antenna used for power transmission, and information about the power transmitting unit (power transmitting circuit) used for power transmission.

[0098] The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0099] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0100] 100: Power transmitting device (TX), 200~220: Power receiving device (RX)

Claims

[Claim 1] A power transmission device, power transmitting means for wirelessly transmitting power to one or more power receiving devices; a communication means for communicating with the one or more power receiving devices; a derivation unit that derives data on power loss between the power transmitting unit and the power receiving unit based on a value of received power received from the power receiving unit via the communication unit; a foreign object detection means for detecting an object other than the power receiving device that performs the communication based on the data of the power loss; a detection means for detecting a change in a power transmission and reception state within a power transmission range of the power transmission device, When the detecting means detects a change in the power transmission / reception state while the power transmitting means is transmitting power to the power receiving device, the deriving means re-derives the data of the power loss. A power transmission device characterized by:

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